The present invention relates generally to an air bag assembly. More specifically, the present invention relates to an air bag assembly utilizing one or more extendible tethering elements providing adjustable cushion depth. The tethering elements are held in anchored relation to a support structure adapted to be selectively secured against withdrawal during air bag deployment depending upon vehicle and occupant conditions.
It is well known to provide an air bag assembly including an inflatable cushion for protecting one or more occupants of a transportation vehicle. In an automotive vehicle, such air bag assemblies are typically positioned within the hub of the steering wheel and within a recess in the instrument panel so as to protect occupants seated in opposing relation to such assemblies. Additional air bag assemblies may be positioned within the seats and/or door panels of the vehicle for protecting the occupants during a side-impact event. It is also known to use inflatable curtain-like structures for deployment from the structural pillars and/or roof-area of the vehicle, promoting the restraint and protection of the occupants during a roll-over event.
An air bag assembly typically includes an inflatable cushion in fluid communication with a gas-emitting inflator. Upon sensing predetermined vehicle conditions, such as a given level of vehicle deceleration, the inflator discharges a fixed amount of gas, thereby forcing the cushion into a deployed position. The gas occupies the available volume within the cushion, thereby forcing the cushion to expand outwardly to the extent permitted by its construction. As an occupant comes into contact with the inflated cushion, the gas is forced out of the air bag, thereby dissipating the kinetic energy of the occupant and achieving a so-called xe2x80x9cride-downxe2x80x9d effect.
It has been recognized that in some instances it may be desirable to adjust the inflation characteristics of the air bag to reflect the nature of the impact event, the size of the occupant (height and/or weight), the seating position of the occupant, and/or the seat-belt use/non-use of the occupant to be protected. In order to provide a degree of control over the pressure within the air bag, it is known to use an inflator that has varying levels or stages of gas output associated with the sensing of different vehicle and/or occupant conditions. Thus, it is known to utilize so-called xe2x80x9cdual-stagexe2x80x9d inflators. These dual-stage inflators, however, are more complex than typical inflators and are capable of providing only discrete levels of gas output.
In order to provide additional control over the inflation characteristics of the air bag it has been suggested to utilize extendible tethering elements in the form of straps or webs spanning the surfaces of the air bag that may be released from a first restrained operative length to a second extended operative length upon the occurrence of vehicle and/or occupant conditions warranting an increased air bag profile. It has also been suggested to utilize cushions that incorporate sewn or woven seams to control the expanded geometry of the air bag, wherein the seams may separate upon the introduction of pressures exceeding a predetermined level, thereby freeing the cushion from restraints imposed by the seams at lower pressures.
The present invention provides advantages and alternatives over the prior art by providing an air bag assembly utilizing a releasable bracket structure operatively connected to one or more extendable tethering elements and providing adjustable cushion depth. A release element selectively engages or disengages the bracket structure during operation of the vehicle taking into account steady-state inputs such as occupant size, seating position, and seat-belt use. The release element may be automatically engaged or disengaged from the bracket as occupant and/or driving conditions change prior to actual air bag deployment.
According to one aspect of the invention, an air bag assembly operable for providing the cushioning restraint of a vehicle occupant during an impact event is provided. The air bag assembly includes an inflatable air bag cushion having a first expanded profile and a second expanded profile, wherein the first expanded profile is characterized by relatively less air bag cushion depth than the second expanded profile. The air bag assembly also includes a tethering element coupled to the air bag cushion, wherein the tethering element has a first configuration associated with the first expanded profile of the air bag cushion and a second configuration associated with the second expanded profile of the air bag cushion. The air bag assembly further includes a restraining assembly operatively coupled to the tethering element, wherein the restraining assembly is operable for selectively enabling/disabling the first configuration and the second configuration of the tethering element based upon steady state conditions of the vehicle and occupant to be protected.
Advantageously, the air bag assembly of the present invention provides a relatively simple, cost-effective, and highly reproducible mechanism for controlling and adjusting the inflation characteristics of an air bag cushion.